Power tool

Abstract

A power tool includes a case, a motor, a plurality of Hall effect sensors, a first circuit board, and a second circuit board. The Hall effect sensors detect a position of a rotor of the motor and correspondingly generate position signals. A plurality of commutating switches and a first controller are disposed on the first circuit board. A second controller is disposed on the second circuit board, and could transmit a driving signal to the first controller according to the operating signal of an operator interface. The first controller regulates the commutating switches to commutate according to the driving signal and the position signals, thereby to activate the rotor to rotate. With such design, a commutation process and a user operating process are regulated by the two different controllers, which could efficiently simplify the program code installed in each of the controllers and facilitate the maintenance of the controllers.

What is claimed is: 
     
       1. A power tool, comprising:
 a case, which comprises a transmission portion, a holding portion, and a bottom, wherein the holding portion is disposed between the transmission portion and the bottom, and the bottom of the case is adapted to be coupled to a battery pack; 
 a motor, which is mounted in the transmission portion; 
 a plurality of Hall effect sensors, which are mounted in the transmission portion and are adapted to detect a position of a rotor of the motor, thereby to correspondingly and respectively generate a position signal; 
 a first circuit board, which is arranged in the holding portion, wherein a plurality of commutating switches and a first controller are disposed on the first circuit board; the first controller is electrically connected to the plurality of commutating switches and the plurality of Hall effect sensors; the plurality of commutating switches are electrically connected to the motor; the first controller receives a driving signal and regulates the plurality of commutating switches to commutate in accordance with the driving signal and the position signal, thereby to activate the rotor of the motor to rotate; and 
 a second circuit board, which is arranged in the bottom of the case and which is electrically connected to the first circuit board by a transmission wire assembly, wherein a second controller is disposed on the second circuit board, and transmits the driving signal to the first controller via the transmission wire assembly; 
 an operator interface mounted on the case and adapted to be operated to generate an operating signal, wherein the second controller is electrically connected to the operator interface; 
 wherein when the operator interface is operated to generate the operating signal, the second controller receives the operating signal and converts the operating signal into the driving signal; 
 wherein an output of each of the plurality of Hall effect sensors is shifted between a first voltage level and a second voltage level; and 
 wherein in a process of converting the plurality of position signals into a rotational speed signal by the first controller, the first controller changes the rotational speed signal from a third voltage level to a fourth voltage level when the output of each of the plurality of Hall effect sensors is shifted from the first voltage level to the second voltage level, and the first controller changes the rotational speed signal from the fourth voltage level to the third voltage level when the output of each of the plurality of Hall effect sensors shifts from the second voltage level to the first voltage level; and the rotational speed signal merely switches between the third voltage level and the fourth voltage level. 
 
     
     
       2. The power tool of  claim 1 , wherein an angle formed between an extension line of the first circuit board and a horizontal axis of the transmission portion is between 85 and 80 degrees. 
     
     
       3. The power tool of  claim 1 , wherein the rotational speed signal is transmitted to the second controller via the transmission wire assembly; the second controller determines a rotational speed of the motor according to the rotational speed signal. 
     
     
       4. The power tool of  claim 1 , further comprising a temperature sensor disposed in the transmission portion to detect a temperature of the motor. 
     
     
       5. The power tool of  claim 4 , wherein the temperature sensor is electrically connected to the first controller, and generates a temperature signal after detecting the temperature of the motor; the temperature signal is transmitted to the second controller via the transmission wire assembly. 
     
     
       6. The power tool of  claim 4 , wherein the temperature sensor comprises an NTC-resistor. 
     
     
       7. The power tool of  claim 1 , wherein the driving signal comprises a speed command. 
     
     
       8. The power tool of  claim 7 , wherein the speed command is transmitted in a way of PWM. 
     
     
       9. The power tool of  claim 1 , wherein the driving signal comprises a rotation direction command and a braking command.